1. Technical Field
The present invention relates to a liquid ejection head such as an ink jet recording head and a liquid ejection apparatus having the same, and more specifically to a liquid ejection head that introduces a liquid from a liquid containing member into a pressure chamber and ejects the liquid from the pressure chamber through nozzles by driving a pressure generating unit, and a liquid ejection apparatus having the same.
2. Related Art
Liquid ejection apparatuses generally have a liquid ejection head and are configured to eject various liquid from the ejection head. Such liquid ejection apparatuses include, for example, image recording apparatuses such as an ink jet printer and an ink jet plotter. Recently, liquid ejection apparatuses are applied to various manufacturing apparatuses by taking advantage of ability to precisely eject an extremely small amount of liquid onto a predetermined position. For example, liquid ejection apparatuses are applied to display manufacturing apparatuses for manufacturing color filters of liquid crystal displays, electrode manufacturing apparatuses for manufacturing electrodes of organic EL (electroluminescence) displays or FEDs (field emission displays), and chip manufacturing apparatuses for manufacturing biochips (biochemical chips). Further, the recording head for image recording apparatuses ejects ink in a liquid form, and the color material ejection head for display manufacturing apparatuses ejects the respective color material solution of R (Red), G (Green) and B (Blue). The electrode material ejection head for electrode manufacturing apparatuses ejects an electrode material in a liquid form, and the bio-organic material ejection head for chip manufacturing apparatuses ejects a bio-organic solution.
Liquid ejection apparatuses of the above-mentioned type have been developed as the apparatuses that use a cartridge-type liquid containing member, which is easily distributed and handled. For example, ink jet printers (hereinafter, simply referred to as printers) that use ink cartridges for containing ink in a liquid form are widely available. In a printer of this configuration, when ink cartridges are loaded in a recording head which is a type of liquid ejection head, ink introduction needles (liquid introduction needles) of the recording head are inserted into the respective ink cartridges, thereby allowing ink to be introduced from the ink cartridges into the recording head through ink introduction holes (liquid introduction holes) that are formed at the tip end of the ink introduction needles. The ink which has been introduced into the recording head is then introduced into common liquid chambers (also referred to as reservoirs or manifolds) via introduction paths in the recording head. The ink which has been introduced into the common liquid chambers is then supplied to a plurality of pressure chambers that communicate with the common liquid chambers. Then, piezoelectric transducers or heat generating elements which are a type of pressure generating unit are driven to generate pressure changes in the pressure chambers. The ink droplets are ejected through nozzles that communicate with the pressure chambers by controlling the pressure changes in the pressure chambers.
In some cases, an excessive positive pressure or negative pressure may be created in the ink cartridge due to fluctuation of temperature or atmospheric pressure, and when such pressure is transmitted from the ink cartridge to the nozzles of the recording head, menisci formed at the nozzles may be broken. That is, a meniscus may be excessively withdrawn into the pressure chamber from the inner rim of the nozzle, or alternatively, may outwardly expand from the nozzle opening on the ejection side. When the pressure of the meniscus is beyond the level of pressure resistance, the meniscus may not be appropriately formed, that is, the meniscus may be broken, thereby leading to a failure of ink ejection, so-called missing dots. Further, there is a risk that ink may leak from the nozzles. In order to overcome such problems, JP-A-2008-162217 discloses providing a pressure control valve on the ink cartridge (ink tank) that is capable of allowing the air layer in the cartridge to be open to the atmosphere, so that variation in pressure in the ink cartridge is reduced by opening the pressure control valve when an excessive pressure is generated in the ink cartridge due to fluctuation of temperature or the like.
In the above-mentioned configuration in which air layer is open to the atmosphere by using a pressure control valve, relatively small pressure changes, such as those due to fluctuation of temperature or atmospheric pressure, can be accommodated. However, it may not be possible to adequately address more instantaneous fluctuations of pressure, for example, the case where an impact such as an external force is applied to the ink cartridge during the exchange of ink cartridges, or where the relative positions of the ink cartridge and the recording head are changed due to any vibration.
The situation such as those described above may occur not only in the exemplified ink jet recording apparatus, but also in other liquid ejection apparatuses that are configured to introduce a liquid from the liquid containing member into the liquid ejection head.